The objectives of this research project are to investigate the effects of alcohol on cognitive and perceptual-motor performance in human female subjects during the menstrual cycle. Three groups of females will receive alcohol and one group will receive a placebo with 20 subjects per group. Each subject will be tested during the menstrual flow period, the ovulatory period and the premenstrual period. The first testing session will be on a different day of the menstrual cycle for each alcohol group in order to control order and practice effects. Two groups of male subjects (20 per group) will be given either an alcohol or a placebo dose and will be compared to the performance of the female subjects. A verbal memory task and a choice reaction time task will be administered before alcohol (baseline) and also after alcohol (0.66 ml/kg) on the ascending and descending limbs of the blood alcohol curve. Blood alcohol variables such as absorption rate, elimination rate and peak blood alcohol level will be determined for each subject. A second study will involve administering alcohol for 30 days to five regularly menstruating women, five women on the birth control pill and five post-menopausal women and determining the relationship of plasma estrogen and progesterone levels to blood alcohol variables and reaction time performance. Five males also will be included as a comparison group. The third study will be similar to the second study except female alcoholics will be tested to determine if their sex hormonal levels are different from nonalcoholic women. Possible differences between the effects of alcohol on male and female alcoholics also will be evaluated. Results of these three experiments will provide information on the relationship between days in the menstrual cycle (hormonal changes) and performance during acute alcohol intoxication. It may be found that alcohol tolerance, and thus addiction, may be related to the fluctuating sex hormonal levels in females.